MICHELE KELEMEN, BYLINE: As she prepares to pass the baton to Kerry, Secretary Clinton shared with Congress a bit of parting advice. She says the U.S. has to continue to lead.

SECRETARY OF STATE HILLARY CLINTON: We've come a long way in the past four years. And we cannot afford to retreat now. When America is absent, especially from unstable environments, there are consequences. Extremism takes root, our interests suffer, our security at home is threatened.

KELEMEN: She says the U.S. is now investigating reports that some of the attackers in Benghazi were also involved in the recent hostage taking in Algeria, where three Americans were killed. There's no doubt, Clinton says, that Libyan weapons were used in Algeria, as well as in Northern Mali, where al Qaida in the Islamic Maghreb has found safe haven.

And the U.S., she says, needs a strategy to deal with what she calls a spreading jihadist threat in a new political landscape.

CLINTON: The Arab revolutions have scrambled power dynamics and shattered security forces across the region. Instability in Mali has created an expanding safe haven for terrorists who look to extend their influence and plot further attacks of the kind we saw just last week in Algeria.

KELEMEN: The ranking Republican on the Senate Foreign Relations Committee, Bob Corker of Tennessee, says the attack in Benghazi, Libya symbolizes how woefully unprepared the U.S. was.

REPRESENTATIVE BOB CORKER: To look at the faces of those on the ground in Libya, in a state of shock. People that we sent there, doing expeditionary diplomacy, who felt like they were on a tether and candidly did not have the support from Washington that they needed to do the things they needed to do.

KELEMEN: Corker says he hopes the incoming secretary will learn from what happened. Secretary Clinton says he'll be dealing with a situation no one predicted - dramatic changes in Egypt, Libya and Tunisia.

CLINTON: When I was here four years ago, testifying for my confirmation, I don't think anyone would have thought that Mubarak would be gone, Qaddafi would be gone, Ben Ali would be gone; that we would have such revolutionary change in this region.

KELEMEN: She calls it a great opportunity and a serious threat. Though many members of Congress praised Clinton for her tenure at state, Benghazi casts a shadow over her legacy. A Republican congressman from South Carolina, Jeff Duncan, says Clinton should have read the cables requesting more security.

REPRESENTATIVE JEFF DUNCAN: Madame Secretary, you let the consulate become a death trap. And that's national security malpractice.

KELEMEN: Senator Rand Paul of Kentucky suggested she should have been fired. Clinton lost her temper only at one point, when Wisconsin Republican Ron Johnson pressed her on why the administration initially said the attack in Benghazi grew out of a protest over an anti-Islam video.

REPRESENTATIVE RON JOHNSON: Johnson: We were misled that there were supposedly protests and then something sprang out of that, an assault sprang out of that. And that was --

CLINTON: But not...

JOHNSON: ...Al Qaeda. That was not the facts.

CLINTON: But, but, you know...

JOHNSON: And the American people could have known that within days.

CLINTON: And...

JOHNSON: And they didn't know that.

CLINTON: With all due respect, the fact is we had four dead Americans.

JOHNSON: I understand.

CLINTON: Was it because a protest or was it because of guys out for a walk one night who decided they'd go kill some Americans. What difference, at this point, does it make?

KELEMEN: It's more important, she says, to find the perpetrators. so far no one has been brought to justice for carrying out the attack. Michele Kelemen, NPR News, Washington. Transcript provided by NPR, Copyright NPR.